clean up old Jenkins resources (#40920)

* clean up old Jenkins resources

* clean up groovy scripts and other .ci resources

---------

Co-authored-by: julienlind <vincent.lind@elastic.co>

.buildkite/aws-tests-pipeline.yml

@@ -19,7 +19,7 @@ env:
 steps:
   - label: ":ubuntu: x-pack/filebeat: AWS Tests"
     key: "x-pack-filebeat-extended-cloud-test"
-    skip: "skipping as it was on Jenkins: elastic/ingest-dev#3467"
+    skip: "skipping:  elastic/ingest-dev#3467"
     # Related issue: https://github.com/elastic/ingest-dev/issues/3467
     env:
       MODULE_DIR: "x-pack/filebeat/input/awss3/_meta/terraform"

.buildkite/x-pack/pipeline.xpack.filebeat.yml

@@ -292,7 +292,7 @@ steps:
 
       - label: ":ubuntu: x-pack/filebeat: AWS Tests"
         key: "x-pack-filebeat-extended-cloud-test"
-        skip: "skipping as it was on Jenkins: elastic/ingest-dev#3467"
+        skip: "skipping: elastic/ingest-dev#3467"
         # Related issue: https://github.com/elastic/ingest-dev/issues/3467
         if: build.env("GITHUB_PR_LABELS") =~ /.*aws.*/
         env:

.buildkite/x-pack/pipeline.xpack.heartbeat.yml

@@ -130,7 +130,6 @@ steps:
           - github_commit_status:
               context: "x-pack/heartbeat: Win 2016 Unit Tests"
 
-      # Doesn't exist in Jenkins
       - label: ":windows: x-pack/heartbeat: Win 2022 Unit Tests"
         key: "mandatory-win-2022-unit-tests"
         command: |
@@ -178,7 +177,6 @@ steps:
           - github_commit_status:
               context: "x-pack/heartbeat: Win 10 Unit Tests"
 
-      # Doesn't exist in Jenkins
       - label: ":windows: x-pack/heartbeat: Win 11 Unit Tests"
         command: |
           Set-Location -Path x-pack/heartbeat